What to Ask to a Peer: Query Reformulation over Ontology-based Peers

Diego Calvanese, Giuseppe De Giacomo, Domenico Lembo, Maurizio Lenzerini, and Riccardo Rosati

2006. Manuscript.

In the recent years, the issue of cooperation, integration, and coordination between information peers has been addressed both in the context of the Semantic Web, and in several other networked environments, including data integration, Peer-to-Peer and Grid computing, service-oriented computing and distributed agent systems. One of the main problems that arises in such contexts is how to exploit the mappings between peers in order to answer queries posed to one peer. The goal of this paper is to present some basic, fundamental results on this problem. In particular, we focus on a simplified setting based on just two interoperating peers, and we investigate how to solve the so-called "What-To-Ask" problem: find a way to answer queries posed to a peer by relying only on the query answering service available at the queried peer and at the other peer. We show that a solution to this problem exists in the case of peers based on a basic ontology language, and we provide an algorithm to compute it. We also discuss cases that show that, by slightly enriching the ontology language, the problem may become unsolvable.

   title = "What to Ask to a Peer:  Query Reformulation over Ontology-based
   year = "2006",
   author = "Diego Calvanese and De Giacomo, Giuseppe and Domenico
Lembo and Maurizio Lenzerini and Riccardo Rosati",
   note = "Manuscript",